Acyloxymethylene-pentenoates



i atented jan. 30,

2,540,070 ACYLOXYMETHYLENE-PENTENOATES Willard J. Croxall, Bryn Athyn, and John 0. Van Hook, Philadelphia, Pa., assignors to Rohm & Haas Company, Philadelphia, Pa., a corporatio of Delaware No Drawing. Application January 21, 1949, Serial No. 72,075

This invention relates to 2-acyloxymethylene- 4-pentenoates and to a process for their preparation. These compounds are formed by reacting an ester of a 2-hydroxymethylene-4-pentenoic acid and a non-tertiary monohydric alcohol with an anhydride of a carboxylic acid. Thus, an ester of the formula HO OH=CC o o R o R (1112 is reacted with a carboxylic anhydride,

(R' 'CO) 20 to form the acid, RCOOI-I, and the compound containing two ester groups,

wherein R is a non-tertiary hydrocarbon group, R and R are members of the class consisting of hydrogen, chlorine, bromine, the phenyl group, and alkyl groups of not over four carbon atoms, and R" is a hydrocarbon group, particularly an alkyl group of not over three carbon atoms. These new diesters are useful chemical intermediates, plasticizers, and softeners. They react, for instance, with carbamides and thiocarbamides to form uracils and thiouracils. 'By hydrolysis they form the free hydroxymethyleneipentenoic acids which are decarboxylated by heating to yield terminally unsaturated aldehydes,

OHC'CH2CH(R C(RF) =CH2 When heated with an alcohol, R'OH, in the presence of an acidic catalyst, such as p-toluene sulfonic acid, they are converted to ether esters,

R'OCH=O-GO0R(or R) HOB! R2 Hz which form the subject'of our application Serial No. 72,074, filed on even date.

The preparation of the 2-hydroxymethylene- 4-pentenoates, which are here reacted with a carboxylic acid anhydride, forms the subject matter of our application Serial No. 72,076, filed 6 Claims. (C1. 260-484) on even date. These starting materials are availpractical source, they are obtainable through the reaction of acetylene and an ester of carbonic acid in the presence of an alkaline catalyst to form'beta-ether acrylates and propionates with the introduction of 2,3-unsaturated groups therein and the rearrangement of these beta-ether acrylates to esters of Z-hydroxymethylene- 4-pentenoic acids by heating at to 250 C.

As shown in application Serial No. 52,607, filed by Croxall and Schneider on October 2, 1948, acetylene reacts with an ester of carbonic acid and a non-tertiary alcohol in the presencce of an anhydrous, strongly alkaline catalyst to form betaether acrylate'and beta,betadiether propionate. When diallyl carbonate is used, for example, there are obtained allyl beta-alloxyacrylate and allyl beta,beta-dialloxypropionate. Other 2,3- unsaturated residues may be used in the place of the allyl group just shown.

Unsaturated ether esters need not, however, be thus directly prepared. As a starting carbonate there maybe taken an ester of a lower saturated aliphatic monohydric alcohol and carbonic acid, such as dimethyl carbonate, diethyl carbonate, dipropyl carbonate, dibutyl carbonate, dihexyl carbonate, or dioctyl carbonate. These yield by reaction with acetylene in the presence of the alkaline catalysts corresponding alkyl betaalkoxyacrylates and beta,beta-dialkoxypropionates. When these are heated with a 2,3-unsaturated alcohol in the presence of an alkaline catalyst, the groups from the lower boiling alcohols are displaced by a higher boiling unsaturated alcohol, as described in application Serial No. 52,601, filed by Croxall and Van Hook on October 2, 1948.

It is not necessary, however, to replace both ether and ester group. The alkyl group completing the ether function is replaced when a beta-alkoxyacrylate or beta,beta-dialko'xypropionate is heated with a 2,3-unsaturated alcohol in the presence of a mildly acidic catalyst, such as an alkali metal acid sulfate. There is taken from the reaction mixture the alcohol corresponding to the alkyl group. When an amount of such alcohol as is equivalent to the ether group has been removed, the reaction is interrupted. In this way ether esters of the formulae R'OCH=CI-ICOOR and (RO) 2CHCH2COOR are obtained, as is more fully described in application SerialNo. 52,602, filed by Croxalland Van Hook on October 2, 1948. R is used above 3 to designate the olefinically unsaturated Tgroup introduced.

The beta,beta-diether propionates are converted to beta-ether acrylates when the former arc); ted in the presence of a dealcoholating ca alyst, such as an alkali or an alkali metal acid sulfate, and a mole of alcohol is taken offper mole of ester. This process is described in application Serial No. 52,608, filed by Croxall and,

Schneider on October 2, 1948. By this process a diether ester, such as ethyl diethoxypropionate, is converted to the corresponding acrylate, ethyl beta-ethoxyacrylate, or allyl dialloxypropionate to allyl beta-alloxyacrylate.

In place of the illustrative allyl group which has been the only one thus far given, there may be introduced other allylicly unsaturated'g'roup, particularly a hydrocarbon group or a halohydrocarbon group; i. e., a 2,3-unsaturated' group. Preferred unsaturated groups are allyl, 2-methallyl, 2-ethallyl, 2-propally1, 2-butallyl,' Z-phenallyl, 2-chloroallyl, Z-bromoallyl, 3-methal1y1 .(crotyl), 3-ethallyl, 3-propallyl, 3-butallyl,' and 3-phenallyl (cinnamyl). These are residues of alcohols of the formula Such residue is most conveniently and economically introduced through transetherification of an alkyl beta-alkoxyacrylate or an alkyl beta,beta-dialkoxypropionate, accompanied by dealcoholation. Instead of a single pure betaalkoxyacrylate or beta,beta-dialkoxypropionate, there may be used a mixture of'the two, as is frequently obtained fromreaction of dialkyl"car- 5? bonate and acetylene. The alkyl groups are preferably not over eight carbon atoms in size. By this reaction there result compounds of the formula R CH=C (R cnzocn cn'coon Where R is analkyl group of not over eight carbon atoms and R and R have the significance given above. It is desirable that during tran'setherification the reaction temperature be maintained be--* low 150 C. if the above compounds are to'be isolated. The stripping of the alcohol displaced,

ROH, is, therefore, advantageously accomplished under reduced pressure. v

One may thus start with an' ester',"(RO) 2C0; of carbonic acid and a saturated non-tertiary a1- cohol, ROH, where'R is in particular *an, alykl "group of not over eight carbon atoms and'preferably of not over four carbon atoms. Byfreaction thereof with acetylene at 20 Cl to 110 C.

in the presence of a strongly alkaline'" catalyst, such as an alkali metal acetylide, an alkali alcoholate, or a strongly basic quaternary ammonium alkoxide, there are obtained such acrylates as methyl beta-methoxyacrylate, ethylbetaethoxyacrylate, propyl beta'propoxyacrylate,'.bu-

tyl beta-butoxyacrylate, hexyl jbeta-hexoxyacrylate, or octyl beta-octoxyacrylate, orsfuch'promixture may be used directly in subsequent steps or separated or the propionate decomposed to ether acrylate.

The ether acrylate or the mixture may then be transetherified by heating it with a beta,gamma.. unsaturated alcohol, such as'allyl, Z-chloroallyl, 2.-brom'oallyl, 2-methallyl,2'sbutallyl; crotyl, cinnamyl alcohols, or z-penten-l-ol, 2-hexen-1-ol, or the like. A mildly acidic catalyst is used at a concentration of 0.01% to 1% of the weight of the ether ester. The alcohol ROH is displaced at temperatures between 75 C. and 150 C. at normal or reduced pressure. of the ether ester RVOCH=CHCOOR (or R) This permits isolation I The product is then heated at 150 C. to 250 C.,

' preferably 150 C. to 200 C., and is thereby rearranged. The ester of 2-hydroxymethylene-4- pentenoic acid'which' results is separated.

Alternatively, the alkyl beta-alkoxyacrylate"'or dialkoxy propionate is'heated at 150 C. to 250C.

'in the presence of an alkali metal acid sulfate with a beta,gamma -unsaturated alcohol, RGH, where R is the beta,gamma-unsatur ated residue. Transetherification and rearrangement'bothtake place in the reaction mixture. The displaced alcohol is distilled off, the catalyst is destroyed, and the rearranged product is worked up.

Similarly, an alkyl beta-alkoxyacrylate is heated to 150 C. to 250 C. with a beta,gamma-unsaturated alcohol in--,the presence of an; alkaline catalyst. Transetherification and transesterification now both take place accompanied by rearrangement of the unsaturated groupintroduced through the ether function. Underthese conditions there can be isolated not only some transetherified and transesterified acrylates but also 2-hydroxymethylene-4-pentenoates and/or on continued heating 4-pentenoates. The last result from the decarbonylation of the 2-hydroxymethylene-4-pentenoates through heating in the presence of alkali.

EXAMPLE A (0,) Preparation of ethyl b eta allozryacrylate Amixture of 144g'rams of ethylbeta-ethoxyacrylate, 174 grams of allyl alcohol, and 0.1 gram of sodium hydrogen sulfate was heated in a reaction vessel carrying a distillation column. After a short period of heating there was evolved ethyl alcohol which was taken oil at an overhead temperature of 78-79 C. with a pot temperature of about C. The pot temperature gradually rose .to C.- while there were taken off 41 grams of ethyl alcohol and then 21 grams of a mixture of ethyl alcohol and'allylalcohol, the latter distilling at 80 to 94 C. The-reaction mixture was then subjected to distillation under reduced pressure. A'fraction distilling at 25 to 40 C./22 mm. was identified as allyl alcohol. Between 51 and 68 C./3 mm. a mixture of allyl alcohol and ethyl beta-alloxyacrylate was taken off. Then, the main 1. fraction of ethyl betaalloxyacrylate was distilled at 65-72 C./2-3

beta-alloxyacrylate.

The main fraction wasredistilled at 73 C./ 3 mm. The product thus obtained had a'refrac- .75 tive index of 1.4640 and a saponificationiequivw lent of 157. The 7' theoretical saponification equivalent for ethyl beta-alloxyacrylate is 156.

(b) Rearrangement of ethyl beta-alloxyacrylate to ethyl 2-hydroarymethylene-4-pentenoate Pure ethyl beta-alloxyacrylate, prepared as described immediately above, was taken in an amount of 312 grams. Thereto was added 5 grams of beta-naphthol and the mixture was heated at 150 C. (15 C.) for two hours with stirring. This mixture was then cooled to 10 C. and stirred at 10 C. for one-half hour with a solution of 80 grams of sodium hydroxide in 500 ml. of water. The resulting mixture was then allowed to stand. Two layers formed and were separated. The lower aqueous layer was shaken with ether and the ether extract was added to the organic layer. The latter was then dried over potassium carbonate and distilled. Therefrom was recovered 43 grams of ethyl, betaalloxyacrylate, distilling at 60-70 C./0.7 mm.

To the aqueous layer there was added hydrochloric acid until the layer was distinctly acidic. An organic layer formed andwas separated after it had been taken up in ether. The ether solution was dried over a calcium sulfate drying agent and subjected to distillation. After the ether had been stripped off, a fraction was obtained at 639-76? C./2.5 mm. which corresponded approximately in composition to ethyl 2-hydroxymethylene-4-pentenoate. This fraction was redistilled and the fraction coming over at 46-47 C./1 mm. was collected. It had a refractive index, a of 1.4565 and a density,

of 1.040. It contained by analysis 61.83% of carbon and 7.85% of hydrogen, compared to theoretical values forethyl 2-hydroxymethylene-4-pentenoate of 61.51% and 7.74% respectively.

There may similarly be prepared methyl betaalloxya'crylate, propyl beta-chloroalloxyacrylate, butyl beta-chloroalloxyacrylate, or other alkyl beta-alloxyacrylate, which may in turn berearranged by heating to an alkyl 2-hydroxymethylene-4-pentenoate, as above. Typical of these is v the following preparation.

EXAIVIPLE B (a) Preparation of methyl beta-alloayacrylate A mixture of 116 grams of methyl beta-methoxyacrylate, 108 grams of allyl alcohol, and 0.1 gram of sodium hydrogen sulfate was heated in a reaction vessel carrying a packed distillation column. When the reaction mixture reached a temperature of about 80 C., methyl alcohol began to be evolved. It was taken off at overhead temperatures of 64 to 67 C., while the pot temperature was carried above 100 C. The reaction mixture was then subjected to distillation through a two-foot column under reduced pressure. Excess allyl alcohol was taken off. There was then obtained a fraction of 56 grams, distilling at 57-63 C./2-4 mm. This fraction had a. refractive index, n of 1.4675, molecular refraction, MR1), of 37.43, a density,

of 1.054, and a saponification equivalent of 145. Theoretical values for methyl beta-alloxyacrylate (CqHioOa) are for MR1), 36.89, and for saponification equivalent, 142.

Continued distillation yielded 60 grams of a mixture of methyl beta-alloxyacrylate and allyl A portion of the above methyl beta-alloxy-- acrylate was heated at 150 C. for three and onehalf hours. The reaction mixture was then distilled and four grams of an oil obtained at 40- 45 C./2-3 mm.- which corresponded approximately in composition to methyl-z-hydroxymethylene-4-pentenoate.

In the following example there is used crotyl alcohol as typical of the 2,3-unsaturated alcohols, R CH=C(R )CH2OH wherein R is a hydrocarbon group and R is hydrogen. As will be seen, the R group appears in the pentenoate in the 3- position thereof. In this particular case, R will be methyl, but the same reaction is obtained when R is ethyl, propyl, or butyl, or phenyl, in each case the R hydrocarbon group appearing in the rearranged ester in the 3-position.

The following example illustrates another phase of the reactions here-involved, the use of diether propionates as starting materials and their conversion to ether acrylates as part of the course of the chemical changes leading to the 2-hydroxy-methylene-4-pentenoates.

EXAMPLE'C (a) Preparation of ethyl beta-crotomyacrylate A mixture of 158 grams of ethyl beta,betadlethoxypropionate, 60 gram of crotyl alcohol, and 200 m1. of toluene was treated with 0.1 gram of sodium acid sulfate and heated in" a reaction vessel carrying a two and a half foot column. There were obtained grams of an ethanoltoluene azeotrope which distilled at 74-78 C. and a fraction of 30 grams of ethanol and toluene which distilled at 78 to C. The amount of ethanol taken off was 85 grams (theory for displacement of the ethoxy groups is 75 grams). Distillation was continued under reduced pressure. At 35-40 C./40 mm. afraction consisting of toluene was taken ofi. Between 50 and 71 C./1 mm. there were obtained 55 grams of a mixture of toluene, ethyl beta-ethoxyacrylate, and ethyl beta-crotoxyacrylate. There was then obtained at 71" C./0.9 mm. a fraction of 56 grams of ethyl beta-crotoxyacrylate. It had a refractive index, n of 1.4619 and a saponification equivalent of 172. It contained by analysis 63.75 of carbon and 8.45% of hydrogen.- Theoretical values for ethyl beta-crotoxyacrylate are 63.51% for carbon content, 8.28% for hydrogen content, and for saponification equivalent.

After the above fraction was obtained, there was distilled at 7l-94 C./0.9 mm. a fraction which was found to be a mixture of ethyl betacrotoxyacrylate and crotyl beta-crotoxyacrylate.

(b) Rearrangement to ethyl Z-hydroxymethylene 3-methyZ-4-pentenoate Aportion of 80 grams of ethyl beta-crotoxy acrylate was placed in a flask and heated for 40 minutes at 168-170 C. The contents of the flask were cooled to 10 C. and stirred at 10 C. for 15 minutes with a solution of 30 grams of sodium hydroxide in 270 grams of water. The resulting mixture appeared homogeneous. It was extracted with two 50 ml. portions of ethyl ether. Evaporation of the ether extracts left no residue. The aqueous layer was acidified with dilute hydrochloric acid and an organic layer formed. It was taken up in ether and separated. The water gamma layer was extracted severalfitimeswith sma'lkpon tions of ether, which were combined with the-- mainorganic portions The. combineduether' ex.-.

tracts were dried. over calcium.sulfate-anddistilled. After removal of ether there was obtained a main fraction which distilled-at 40-75 C.'/l mm; This fraction was redistil led-at 60 68=C./ 1

mm. The product had a refractive index, 41

EXAMPLE D (a) There was heated in "a reaction vessel equipped with a. distilling column two feet high a mixture of 144 grams of ethyl beta-ethoxyacrylate, 140 grams of cinnamylalcohol, 100 ml. oftbluene, and 0.1 gram of sodium hydrogen sulfatey' There was taken oil at 74-78 C. an azeotrope of ethanol and toluene in an amount of 53 grams. Between 78 and 110 C. there was taken off a mixture of 7 grams of ethanol and toluene. The pot temperature was then raised to 205 C. to strip offtheu'est of the toluene. Distillation was continued under reduced pressure1-Between55 C. and 126 C./1 mm. there was obtained cinnamyl alcohol, ethyl beta-ethoxyacrylate, and ethyl beta-cinnamoxyacrylate totalling 67 grams. There was then'obtaine'd' a fraction distilling at l26'-l75'C./1 mm. which consisted of ethyl 'beta-cinnamoxyacrylate (86%) and: ethyl 2-hydroxymethylene-3-phenyl=4-pen tenoate:(l4%), as determined by titration The residue was distilled from a vonBraun flaskand at 18 -220 'C./1 mm. a fraction was obtained which consisted of cinnamyl beta-cin-f namoxyacrylate (88%) and cinnamylZ-hydroxymethylene-3-phenyl-4-pentenoate (12%)..

(b) When these fractions were'heated at 170- 200 0., they steadily increased inv acidity as the betaeetheracrylate wasvrearranged: to the 2-hy-' droxymethylene 3-phenyl-4-pentenoa'tes in 'e'ach' case: The final products were ethyl 2-hydroxymethylene-3-phenyl-4-pentenoate and "einnamyl 2-hydroxymethylene-3 phenyl=4-pentenoate' respectively.

In the next two examples the use of a 2-substituent in the 2,3-unsaturated alcohol is shown. This substituent may be a halogen, such as chlorine or bromine, or a hydrocarbon group-such as an alkylgroup of a phenyl group.

EXAMPLE E (a) Preparation of ethyrbetachloroalloxyacrylate anol and toluene, containing 78 gramsof-ethanol. The mixture was then subjectedto-distillation atreduced pressure.

A fraction of 273 ml. of toluenewas distilled at 40 C./40'mm. and

then a fraction of 35- grams of chloroallyl alcohol was taken off at 50 -62 C./2 mm. The next fraction-distilledat 45-80 C./1 mm, was found to- 'cons'ist of ethyl beta-ethoxyacrylate andethyl- There was distilled at -87 C./l mm. a fraction of. 86 grams of ethylbeta-chloroalloxyacrylate.

beta-(beta-chloroalloxy)acrylate. Ithad a refractive index, no, of 1.4800 and contained according to analysis 50.12% of carbon, 5.99% of hydrogen, and 18.65% of chlorine. The theoretical values for ethyl beta-(beta'-chloroalloxy) acrylate are 50.39%, 5.82%, and 18.62% respecl tively.

A final fraction of 35 grams'was distilled at 87 -117 C./1 mm. It was a mixture of ethyl beta-chloroalloxyacrylate and chloroallyl betachloroalloxyacrylate.

(b) Rearrangement" of ethyl betachloroallowyacrylate A portionof 40 grams of ethyl beta-(beta'- chloroalloxy)acrylate was heated at 150-190 C. for ten-minutes and then subjected to distillation under reduced pressure. A fraction of 25 grams was taken off at 45f-160 C./1 mm. This was extracted with ml. of a 10% sodium hydroxide solution and then with-100 ml. of a 5% sodium hydroxide solution. The organic liquid which was separated was unconverted ethyl beta-(beta'- chloroalloxy)acrylate in an amount of 12 grams. The aqueous layer was rendered acidic with hydrochloric acid solution and extracted with ethyl.

ether. The extracts were dried over a calcium sulfate drying reagent and distilled. After removal of ether there was obtained a fraction of five grams of ethyl 2-hydroxymethylene-4-chlo- .ro-4-pentenoate, which distilled at 60-90 C./1

mm. and had a refractive index, no, of 1.4798.

The above procedures were followed in trans- I etherifying butyl beta,beta-dibutoxypropionate with beta-chloroallyl alcohol to yield butyl beta-- (beta'-chloroalloxy) acrylate, which was in turn heated at about 190 C. to cause rearrangement.

The final product was butyl Z-hydroxymethylene- 4 chloro 4 pentenoate distilling at 80100 C./1 mm.

EXAMPLE F Preparation of methallyl 4-methyZ-4-pentenoate and methallyl 2-hydromymethyZene-4-methyl- 4-pentenoate A mixture of 144 grams of ethyl beta-ethoxyacrylate, 170 grams of meth'allyl alcohol in which 5 grams of sodium had been dissolved, and 200 grams of toluene-was heated in a reaction vessel equipped with a two-foot packed column. There was taken off an ethanol-toluene azeotrope (140 grams) at overhead temperatures of 76 to 85'C. with the pot temperature reaching -C. The reaction mixture was cooled and poured into water. The mixture was rendered acidic and the organic layer separated, washed with brine, dried, and distilled. After toluene had been removed,

the remaining liquid was heated at 70 to 170 C. and distilled with overhead temperatures of 40 to C./1 mm. to give a fraction of 134 grams.

This fraction was washedwith 200 ml. of a cold aqueous solution containing 10% of sodium hydroxide. The aqueous and organic layers were separated, the organic layer dried over anhydrous potassium carbonate'and' distilled under reduced pressure. A fraction of 12 grams was obtained at 32-40 C./1 mm. It had a refractive-indexv of 1.4444 and corresponded incomposition to methallyl 4-methyl-4-pentenoate.

This fraction was redistilled at 80 C./9 mm.

It then had a refractive index of 1.4438, a density,

of 0.9103, a molecular refraction, MR1), of 49.08

and asaponification equivalent of 169. Theoretical values are 49.10 for molecular refraction and 167 for saponification equivalent.

There was also obtained 42 grams of methallyl beta-methalloxyacrylate, which distilled at 40- 85 C./1 mm. and had a refractive index, no, of 1.4714. There was further obtained a fraction of 29 grams, distilling at 8590 C./1 mm. which was identified as methallyl beta,beta-di (methalloxy) propionate.

The aqueous layer from the sodium hydroxide wash was rendered acidic with dilute hydrochloric acid and extracted with ethyl ether several times. The extracts were" combined, dried, and distilled. After the ether had been taken off, the product grams) distilled at 64-66 C./1 mm. It was identified as methallyl 2-hydroxymethylene-4-methyl-4-pentenoate.

EXAMPLE G (a) Preparation of allyl beta-alloasyacryla e and beta,beta-di(alloa:y) propionate A mixture of 95 grams of ethyl beta,beta-diethoxypropionate, 200 ml. of toluene, and 63 grams of allyl alcohol in which there had been dissolved 1.5 grams of metallic sodium was heated in a reaction vessel equipped with a two-foot column. There were taken off 90 grams of a toluene-ethanol azeotrope at 7880 C. and 30 grams of a toluene-allyl alcohol mixture at 80-92 C. The pot temperature reached 120 C. The reaction mixture was cooled to room tem-- perature and poured into water. The resulting mixture was neutralized with acid. The organic layer was taken up with ethyl ether to assist in its separation and the aqueous layer extracted with ether. Theorganic layer and ether extract were combined, dried, and distilled. After the ether had been removed, there were obtained between 88 and 115 C. at 1.0 mm. with pot temperatures of 110 to 135 C. 37 grams of a mixture of allyl beta-alloxyacrylate and allyl beta,-, beta-dialloxypropionate.

These products are also obtainable by the direct reaction of diallyl carbonate and acetylene. For example, 213 grams of, allyl alcohol was treated with five grams of sodium in small pieces. When the sodium had all dissolved, excess allyl alcohol was distilled off under reduced pressure. Thereto was added 246 grams of diallyl carbonate. The apparatus was flushed with nitrogen and the batch was maintained at 80-85 C. while acetylene was pressed in at 10 inches mercury pressure. When acetylene was no longer taken up, the batch was cooled, rendered acid by addition of acetic (b) Rearrangement reaction of allyl beta-alloxyacrylate and betabeta-dialloxy propionate as obtained above The mixture was taken upgin 100ml. of toluene and 0.05 gram of sodium acidi'sjulfate added there to. The mixture was then heated underreiiux 1 Preparation "of allyl 10 for an hour and then distilled. Toluene and allyl alcohol were taken off. There was then obtained by distillation 20 grams of product which consisted of 60% of allyl 2-hydroxymethylene-4-pentenoate and 40% of allyl beta-alloxyacrylate, as

determined by analysis.

EXAMPLE H 2-hydroxymethyZene-4-pentenoate There were, mixed 432 grams of ethyl betaethoxyacrylate and 360 grams of allyl alcohol in a reaction vessel equipped with a 35-foot column which was connected to a wet test gas meter. The mixture was heated to reflux and a solution of sodium ethoxide formed by dissolving five grams of sodium in 67 grams of ethanol was introduced in small increments. Ethanol and allyl alcohol were distilled from the mixture and the temperature of the liquid in the reaction vessel was carried up to 172 C. There were taken oil 18.9 liters of carbon monoxide. The liquid was then distilled under reduced pressure. A distillate of 326 grams was obtained at 50-123 C./1 mm. A. tarry residue of 148 grams remained. The distillate was fractionated through a packed column. At 36-'74 C./40 mm. a fraction of 46 grams was obtained. It had a refractive index, n of 1.4140 and corresponded by composition to ethyl 4-pentenoate. A 165-gram fraction distilled at 69-73 C./20 mm., had a'refractive index of 1.4350, and proved to be allyl 4-pentenoate. There was obtained at 62 C./5 mm. to C./1 mm. 69 grams of a mixture of allyl 4-pentenoate and allyl 2-hydroxymethylene-4-pentenoate.

From the esters of z-hydroxymethylenel-pentenoic acid the acylated derivatives are formed by reaction with a carboxylic acid anhydride. While this reaction is a general one for anhydrides of both monocarboxylic acids and polycarboxylic acids, the preferred anhydrides are those from'monobasic carboxylic acids of not over four carbon atoms, acetic, propionic, butyric, and

product and any excess of unreacted anhydride is removed, usually by distillation. The 2-acyloxymethylene-i-pentenoate is then worked up.

The reaction yields compounds of the formula R2 tH. where R is preferably an alkyl group of not over three carbon atoms. R,R, R and 1'1. have meanings given above.

Specific examples illustrating the above procedure follow.

EXAMPLE 1 v A mixture of 157 grams of ethyl Z-hydroxy- .methylene-4-pentenoate and 220 grams of acetic anhydride was formed and heated in a reaction vessel equipped with a distilling column. Acetic acidwas taken off at C. to 0., whereuponhifmixture of acetic acid and acetic an- ;lii 'dride vwas obtained. The reaction mixture abatemen was thenrdistilled 'under irEdllCBdTplBSSuIe. After acetic anhydride had :been .taken ofi, there: was

obtained at 75 C./1 .mm'..11'5 grams of ethyl 2-acetoxymethylene=4-pentenoate, having aire- EXAIVIPLE3 The same procedure was applied 'to a mixture of ethyl 2-hydroxymethylene-4-pentenoate and butyric anhydride." There was obtained at 100- 105 "CJOLS 'mm. ethyl '2-'butyroxy-methylene-4- pentenoate.

In place of ethyl 2 hydroxymethylene-4-pen-. tenoate there may be used the methyL'propyl, butyl, hexyl, octyl, or an allyl'est'er. 'Th'esame sort of reaction occurs with acetic anhydrideyielding alkyl- 2-acetoxymethylene-4-pentenoates. With butyric anhydride th'e'alkyl -(or allyl) 2-butyroxymethylene-4-pentenoates result;

Instead of the alkyl' 2#hydroxymethylene-4- purel was: heated to; ?I5I0 'C;. inra flask-equipped withirafiifour-foot packed ZCOIUIIIII. .There was" taken oil a forerun at 60 to 115 C. At 118- 125 C. there were obtained 76 grams of acetic ;',adi'd :while :the .fpo'ttemperature advanced. to

170 C. The pressurewxithinrthe':apparatus was thenizreducedland excess acetic anhydride taken off. The remaining .material wasxiractionally distilledat lowcpressure. After a smal1 -for.erun

za-fractionzofl lo :grams .wasobtained at 102 pentenoates used above there may be used the 2-hydroxymethylene 4 pentenoates which have R or R substitueritsin the 4- or 3-position's. established above, these groups include-methyl, ethyl, propyl, butyl, and phenyl groups and chlorine and bromine.

By the procedures of examples. directly above thereuwasreactedat 100i'-to l 0.40: grams of acetic. anhydride and 25 grams of. .-=ethy1 :2-hydroxymethylene-3emethyle l pentenoate..- After acetic acid and aceticanhydride had been stripped off, there was: :obtained a fraction: at iC./0.'5-:1 mm.. whichcorresponded in composition to. ethyl 2-acetoxymethylene 3- methyl-4-pentenoate, having a saponification' equivalent? of 525..

Thersamezreaction applied to-ethyl 2-hydroxymethylene- 4-methyl--4-pentenoatev leads; f in the same'wayto ethyl 2-acetoxy-4-methyl 4-pen-- tenoate;

EXAMPLE-"15 .By the procedures just described there was heated "together. 40 grams .of acetic an'hydride andi'20-- grams of ethyl '2-hydroxymethylene-3- phenylil-pentenoate. After acetic acid had been removed and acetic acidan'd acetic anhydride stripped therefrom "at temperatures up to C., there was-"obtained at 100-115 C./0.6-8 mm. a small fraction having a saponification equivalent of 410-iand corresponding to ethyl 2 acetoxymethylene 3 phenyl 4- pentenoate;

:Asl an alternative 'approachto the acylated product, there may be heated together aacarboxylic=acid anhydride and anester-of a betaalloxyacrylic acid. There occurs in separate steps the rearrangement shown above and the acylation without isolation of intermediates.

Temperatures of: to: 200"'C. are-sufficient to saccomplish this result. This :method is "illustrated -inthe following;- examples.

acrylateiand 25'5igrams.iof. acetic-.anhydride i(90i% r 1088 C./2 3Limm .It ahad iawrefractive index of: k460i), la tmolecular refraction -of.51.41- and; a-

densityof 1.056.' t ihad a 'saponificationnumber of 563?:andzan iacid" number ref. 2841-. Itsv carbon "content was 59.86% and.citsrshydrogenxc'ontent was: 1.33%; Th'eproduct was thus 'ethyl. 2-acetoxymethylene-A-pentenoate, for which. corre-.

spending theoretical values :are .-saponification equivalent- 568, acid-x number-284, molecular refraction50-.-'76', carbon 'content-60;59%,;-andhydrogenrcontent-7.l'2%

EXAMPLE 7 Ethyl Z-propionomymethylene-4-pentenoate A mixture-M156 grams (1.0' m'ole) of ethyl beta-alloxyacryl'ate and'195 grams (1.5 moles) of propionic anhydride was heatedin a Claisen flask ,at "172 175? C. while 79 grams (1.07 moles) of propionic acid was distilledoffat 133'-1 10 C. Thishad arefractive index, n 3, of 1.3920. The residue was cooled and the. distillation was continued .in vacuo. After excess propionic.v anhydridewas distilledofi at 35-89 C./0.5

"in ansamount "of- 92. grams, there wa obtained 140 grams (66% .yield) of ethyl .Z-propionoxymethylenei-pentenoate which distilled at 89 97 C./0.5 mm. Onredist-illation, itboiled at 92-94 C./ 0.5 mm..and had an indexof refraction, 12, of 1.4597- and a density,

EXAMPLE 8 Ethyl 2-butyroxymethylene-4-pentenoate A'mixture of 156 grams (1.0 mole.) of ethyl beta-.allox-yacrylate and- 237 grams (l.5.mo1es)-of butyricanhydride was heated in a Claisen flask at .1'Z9-202 C. while 94 grams (1.07 moles) of butyric acid which distilled 3.1)-135154 C. was collected. The residue was cooled and the distillation was continued in vacuo. After removal of .128 grams .of butyric anhydride, which distilled at .46 -95" C.-/0,.5 mm there was obtained 1. As anew-chemical substance, a compound I of the formula RC o o CH=C-C O'OR wherein R is a non-tertiary aliphatic hydrocar= bon-.-gr.oup-..of not over eight carbonatoms, R

is a member of the class consistingoflhydrogen, the methyl group, and the phenyl'group, R is a member of the class consisting of hydrogen, chlorine, andthe'methyI group,-at' least one-of the "groups. B and R being hydrogen, and R---' manalkyltgroup :ofx not over threecarbom atems.

113 2. As a new chemical substance, a compound of the formula CHQC O CH=C-C O O C 11 H H CH 3. As a new chemical substance, a compound of the formula 4. As a, new chemical substance, a compound of the formula 5. A process for preparing 2-acy1oxymethy1ene- 4-pentenoates which comprises reacting together with heating up to 200 C. to complete the re- 14 action an aliphatic monocarboxylic acid anhydride of not over four carbon atoms and an ester wherein R is a non-tertiary aliphatic hydrocarbon group of not over eight carbon atoms, R is a member of the class consisting of hydrogen, the methyl group, and the phenyl group, and R is a member of the class consisting of hydrogen, chlorine, and the methyl group, at least one of the groups R and R being hydrogen.

6. A process for preparing ethyl Z-acetoxymethylene-4-pentenoate which comprises reacting by mixing together acetic anhydride and ethyl 2-hydroxymethylene-4-pentenoate, heating the reaction mixture up to C. to complete the reaction, and separating ethyl 2-acetoxymethylenel-pentenoate.

WILLARD J. CROXALL. JOHN O. VAN HOOK.

No references cited. 

1.AS A NEW CHEMICAL SUBSTANCE. A COMPOUND OF THE FORMULA 